diff --git a/app/helpers/gitlab_routing_helper.rb b/app/helpers/gitlab_routing_helper.rb
index 0517a699ae0..1f7db9b2eb8 100644
--- a/app/helpers/gitlab_routing_helper.rb
+++ b/app/helpers/gitlab_routing_helper.rb
@@ -48,7 +48,11 @@ module GitlabRoutingHelper
   end
 
   def milestone_path(entity, *args)
-    project_milestone_path(entity.project, entity, *args)
+    if entity.is_group_milestone?
+      group_milestone_path(entity.group, entity, *args)
+    elsif entity.is_project_milestone?
+      project_milestone_path(entity.project, entity, *args)
+    end
   end
 
   def issue_url(entity, *args)
@@ -63,6 +67,14 @@ module GitlabRoutingHelper
     project_pipeline_url(pipeline.project, pipeline.id, *args)
   end
 
+  def milestone_url(entity, *args)
+    if entity.is_group_milestone?
+      group_milestone_url(entity.group, entity, *args)
+    elsif entity.is_project_milestone?
+      project_milestone_url(entity.project, entity, *args)
+    end
+  end
+
   def pipeline_job_url(pipeline, build, *args)
     project_job_url(pipeline.project, build.id, *args)
   end
diff --git a/app/views/shared/issuable/_sidebar.html.haml b/app/views/shared/issuable/_sidebar.html.haml
index b08267357e5..e7510c1d1ec 100644
--- a/app/views/shared/issuable/_sidebar.html.haml
+++ b/app/views/shared/issuable/_sidebar.html.haml
@@ -37,7 +37,7 @@
             = link_to 'Edit', '#', class: 'edit-link pull-right'
         .value.hide-collapsed
           - if issuable.milestone
-            = link_to issuable.milestone.title, project_milestone_path(@project, issuable.milestone), class: "bold has-tooltip", title: milestone_remaining_days(issuable.milestone), data: { container: "body", html: 1 }
+            = link_to issuable.milestone.title, milestone_path(issuable.milestone), class: "bold has-tooltip", title: milestone_remaining_days(issuable.milestone), data: { container: "body", html: 1 }
           - else
             %span.no-value None
 
diff --git a/changelogs/unreleased/fix-group-milestone-link-in-issuable-sidebar.yml b/changelogs/unreleased/fix-group-milestone-link-in-issuable-sidebar.yml
new file mode 100644
index 00000000000..1558e575e6d
--- /dev/null
+++ b/changelogs/unreleased/fix-group-milestone-link-in-issuable-sidebar.yml
@@ -0,0 +1,4 @@
+---
+title: Fix links to group milestones from issue and merge request sidebar
+merge_request:
+author:
diff --git a/spec/factories/milestones.rb b/spec/factories/milestones.rb
index 113665ff11b..b5e2ec60072 100644
--- a/spec/factories/milestones.rb
+++ b/spec/factories/milestones.rb
@@ -17,7 +17,7 @@ FactoryGirl.define do
       state "closed"
     end
 
-    after(:build) do |milestone, evaluator|
+    after(:build, :stub) do |milestone, evaluator|
       if evaluator.group
         milestone.group = evaluator.group
       elsif evaluator.group_id
diff --git a/spec/helpers/gitlab_routing_helper_spec.rb b/spec/helpers/gitlab_routing_helper_spec.rb
index 717ac1962d1..9aaed0edf87 100644
--- a/spec/helpers/gitlab_routing_helper_spec.rb
+++ b/spec/helpers/gitlab_routing_helper_spec.rb
@@ -1,6 +1,9 @@
 require 'spec_helper'
 
 describe GitlabRoutingHelper do
+  let(:project) { build_stubbed(:empty_project) }
+  let(:group) { build_stubbed(:group) }
+
   describe 'Project URL helpers' do
     describe '#project_member_path' do
       let(:project_member) { create(:project_member) }
@@ -9,14 +12,10 @@ describe GitlabRoutingHelper do
     end
 
     describe '#request_access_project_members_path' do
-      let(:project) { build_stubbed(:empty_project) }
-
       it { expect(request_access_project_members_path(project)).to eq request_access_project_project_members_path(project) }
     end
 
     describe '#leave_project_members_path' do
-      let(:project) { build_stubbed(:empty_project) }
-
       it { expect(leave_project_members_path(project)).to eq leave_project_project_members_path(project) }
     end
 
@@ -35,8 +34,6 @@ describe GitlabRoutingHelper do
 
   describe 'Group URL helpers' do
     describe '#group_members_url' do
-      let(:group) { build_stubbed(:group) }
-
       it { expect(group_members_url(group)).to eq group_group_members_url(group) }
     end
 
@@ -47,14 +44,10 @@ describe GitlabRoutingHelper do
     end
 
     describe '#request_access_group_members_path' do
-      let(:group) { build_stubbed(:group) }
-
       it { expect(request_access_group_members_path(group)).to eq request_access_group_group_members_path(group) }
     end
 
     describe '#leave_group_members_path' do
-      let(:group) { build_stubbed(:group) }
-
       it { expect(leave_group_members_path(group)).to eq leave_group_group_members_path(group) }
     end
 
@@ -70,4 +63,44 @@ describe GitlabRoutingHelper do
       it { expect(resend_invite_group_member_path(group_member)).to eq resend_invite_group_group_member_path(group_member.source, group_member) }
     end
   end
+
+  describe '#milestone_path' do
+    context 'for a group milestone' do
+      let(:milestone) { build_stubbed(:milestone, group: group, iid: 1) }
+
+      it 'links to the group milestone page' do
+        expect(milestone_path(milestone))
+          .to eq(group_milestone_path(group, milestone))
+      end
+    end
+
+    context 'for a project milestone' do
+      let(:milestone) { build_stubbed(:milestone, project: project, iid: 1) }
+
+      it 'links to the project milestone page' do
+        expect(milestone_path(milestone))
+          .to eq(project_milestone_path(project, milestone))
+      end
+    end
+  end
+
+  describe '#milestone_url' do
+    context 'for a group milestone' do
+      let(:milestone) { build_stubbed(:milestone, group: group, iid: 1) }
+
+      it 'links to the group milestone page' do
+        expect(milestone_url(milestone))
+          .to eq(group_milestone_url(group, milestone))
+      end
+    end
+
+    context 'for a project milestone' do
+      let(:milestone) { build_stubbed(:milestone, project: project, iid: 1) }
+
+      it 'links to the project milestone page' do
+        expect(milestone_url(milestone))
+          .to eq(project_milestone_url(project, milestone))
+      end
+    end
+  end
 end